SurfaceScience21 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 61: Poster Session V: Oxide and insulator surfaces: Structure, epitaxy and growth I
O 61.5: Poster
Mittwoch, 3. März 2021, 10:30–12:30, P
Role of apical oxygen in oxide thin films — •Judith Gabel1, Matthias Pickem2, Philipp Scheiderer3, Marius Fuchs3, Berengar Leikert3, Martin Stübinger3, Lenart Dudy4, Jan M. Tomczak2, Giorgio Sangiovanni3, Karsten Held2, Tien-Lin Lee1, Michael Sing3, and Ralph Claessen3 — 1Diamond Light Source, United Kingdom — 2TU Wien, Austria — 3Universität Würzburg, Germany — 4Synchrotron SOLEIL, France
Owing to their complex phase diagram, transition metal oxides are an interesting playing field for fundamental research but also open up a gateway to novel electronic functionalities. Oxide thin films are of particular importance as they bring along additional parameters to tune the phase diagram. The films are commonly assumed to be stoichiometric and to have an abrupt surface. Using the example of the prototypical correlated metal SrVO3, we demonstrate here that this description overlooks an essential ingredient, apical oxygen adsorbing at the surface, which has to be considered for an accurate description of oxide thin films. The oxygen adatoms, which form even under UHV, change the film stoichiometry and are shown to severely alter the intrinsic electronic structure. They can affect the doping level of the film as well as the energetic order of the atomic orbitals and may lead to the formation of an electronically and magnetically dead surface layer. We demonstrate that, in the presence of apical oxygen, the thickness-dependent metal-insulator transition observed in SrVO3 can no longer be categorized as a purely bandwidth-controlled Mott transition as previously understood.